Automatic tapping machine



July 20, 1943. M. GRAVES AUTOMATIC TAPPING MACHINE Filed July 28, 1942 2Sheets-Sheet l INVENTOR. MARK GRAVES ATTORNEYS July 20, 1943.

M. GRAVES AUTOMATIC TAPPING MACHINE Filed July 28, 1942 2 Sheets-Sheet 2Eli-.2

' INVENTOR.

' MARK GRAVES BY .069 I f A g 1 AT TOR NEYS rotary driven spindle,

Patented July 20, 1943 UNITED, TATES mm AU'roMA'rw 'rAr-rmo MACHVINE v 1Mark Graves, Cleveland Heights, ()hio Application July 28, 1942, SerialNo. 452,513

1 Claim.

This invention relates to the type of tapping machine in which a t ppingtOOLcarriedby-a enters a hole to be tapped, or threaded, cuts a threadtherein to a, desired depth, and then by reversal of the spindle iswithdrawn, and particularly to the type of v such machine wherein theoperation is automatic. 7

An object of the present invention is'to provide novel simple mechanismwhich will automatically,'in continuous operation, feed a tapcarryingspindle downward, and retract same, as a succession of work pieces, fed1y, are tapped.

Another object is the; provision of novel means to preventbreakage ofthe tap, or other part of the machine, when in threading a work-piece.The movement of the tap being automatic it is essential that-provisionbe made whereby movement of the tap isautomatically stopped when astress is imposed which otherwise would cause breakage.

A further object is to support the rotating spindle independently of awork-piece, whereby the spindle controls the advance of a tap,

fect threads.

To the accomplishment of the foregoing and related ends, said invention,then, consists of the means hereinafter fully described and partiou--means to determine readily the stress which will stop the spindle andtap from further rotation until the cause of such stress has beenremoved.

The combination of the invention is completed by mounting a lead screwin fixed relation on the upper end of the spindle and in engagingrelation with the internal threads of a sleeve mounted in fixed relationon the housing of the machine.

The annexed drawings and the following description set forth in detailcertain structure embodying the invention, such' disclosed meansconstitute, however, merely a preferred embodiment of said invention;and, being but one of the various mechanical forms in which theprinciple as its cuts. a thread, thereby insuring the formation of per-'thereto manual an obstruction is encountered 2 cured transversely of thebolt 19 of the invention thereof.

In said drawings: Fig. 1 is an elevational view partly in cross-section;

Fig2 is a cross-sectional view of the clutch'assembly;

maybe used, is not in limitation 'Fig. 3 is a" cross-sectional View ofthe lead.

screw assemblyishowingthe spindle drive;

Fig. 4 is a cross-sectional view on line 4-4 in Fig.2 showing thelockingdevice on the resilient means of the clutch;

Fig. 5 is a top view showing the relation of the locking device to thestud bolt mounting the lead screw element on the spindle; and I I Fig. 6is a cross-sectional view on the line 6-4 in Fig. 3 showing therelationof the parts of the lead screw assembly; I

Referring to the drawings, a housing I is supported on a'column 2 uponwhich a work table 3 is adjustably mounted, in fixed relation. A bracket4 borne by the housing I supports a reversible motor 5, provided with acone pulley 6. A belt I from the pulley 6 drives a cone pulley 8 whichis .rotatably' mounted on a drive shaft 9 which is transversely mountedin the top of housing I on bearings l0.

A drive plate 'H isnon-rotatably mounted on the shaft 9. between pulley8 and housing I. Drive plate II and the adjacent face of pulley .8 areeach provided with suitable clutch facings l2 and a clutch plate 13 isinterposed therebetween as in a conventional clutch construction. Theoutside end of shaft 9 is provided with a thread 14 upon which acastellated nut 15 is mounted with its slots turned toward the pulley 8,and a coiled pressure spring [6 is mounted about shaft 9 between saidnut l5 and a thrust bearing [1 mounted on shaft 9 in engagement withpulley 8. To secure nut IS in a fixed position causing spring 8, theshaft 9 is provided with an internal bore [8 within which a bolt I9 isinserted against the pressure of a spring 20. A lock pin 2| is sein aposition between thrust bearing 11 and nut l5, being inserted through aslot 22 in the side wall of the bore l8.

0n the inside end of shaft/9, and within the housing I, a bevel gear 23is affixed in engagement rotatable relation. The lower end of thespindle 25 is provided with a chuck 25 and a tap 21 in the conventionalmanner.

Hi to exert a desired pressure on the pulley the springs 41 and wm Asplit collar 28 is mounted on top of housing I in concentric relationwith drive gear 24 and spindle 25. An internally threaded sleeve 29 isinserted in said collar 28 and locked therein by means of the bolt andnut assembly 30. Operatively engaging the threads of sleeve 29 is anexternaly threaded lead screw element 3|. A bore 32 partially throughelement 3| is provided with internal splines 33 in engagement withsplines 34 on spindle 2 5. The upper end of pindie is prevmeu'wah, atmeaaea'uen Mr the insertion of a threaded bolt 3|; which is insertedthrough aperture 31 in the closed end 0! element 3| and draws theelement 3| into fix'e'd relation with spindle 25. To provide means forbolt 36, a pair of holes 38 are provided longitudinally of element 3|and in mmemeai relation, the lower portions "0! enlarged providingshoulders 39 against which the heads of pins 40 are urged by springs i.On

the upper ends of pins w a washer 42, provided with a hexagon shapedopening 43, is moi-Hated in a position to engage the hexagon shaped headM of bolt 38. The aim 4A are urged into engagement with shoulders 39 bycoil springs 41 held in the enlarged portion of holes 38 by plugs @5,whereby the washer 42 is held in such position that the hexagon head Ais fitted within the opening 43 in washer 12. 'The lowerportion of head.is rounded as 'shown at 86, permitting ...'ot-a1;ion of head 44 inaperture 43 in washer 42 when the latter is depressed urge of Inoperating the describedfautomatic tapping machine, a tap '2! operative-to out a thread of a a'iesired gauge in an aperture of a w orlnpiecewill be mounted in the chuck .23. A sleeve 2! with an associated leadscrew element i3| will be clamped in the collar 23, the internal of thesleeve and'the external thread of the eleanen't being of the same imageas that or the tap in use. The "spindle 2s will be nrtea inserting thesplihed end thereof within the spline er the i'nt'e'rnei bore 32 inelement 3|. Ahexagon heeaea bolt as win he insertea hreugn thejaisert'ure in in the upper end e: eiemenea ian'a threaded into the bore35 in the en or spindle "25. Asbket wrenchapplied to the'hexagoh head 84of bolt :13 win depress washer into position engaging the roundedportion I501 head I and permit the bolt 36 to draw the element 3| intoclose re- .Zati'oh with spindle is. 'on remev'al of the wrench Washer 12will be lifted by pins to under urge or engage the hexagon head inlocked relation. g

which holes are.-

. mapped berm-e the tab "stood in the art.

In adjusting the clutch, the rod l9 will be pressed inwardly againstspring 20, releasing the nut l5 from its engagement with locking pin 2|.By rotation of the nut I5 the desired pressure is exerted on spring I6which will be transmitted to the clutch assembly. On release rod l9 willbe moved outwardly and pin 2| will engage a slot of the castellated nutl5 locking it against rotation on shaft 9.

v Control of the reversing motor 5 is secured an a dorfleritio' rialmnner with limit switches so mounted 'as to be "engaged by trippingelements carried by the spindle as is well undering no part of thepresent invention an embodiment thereof is not described.

The machine being adjusted and the motor marten, the tap will be enteredinto an aperture of a work-piece positioned on the table 3. Advifice ofthe tap will be controlled by the movevlatent of lead screw element 3|.insleeve 29. When verse hiabhine will .in continuous operationautomatically tap work-pieces placed suce'eeavay in position on thetable 3. If 'andwhen, anything prevents the tee from cutting a Ithread.the clutch will slip and the machine may be is broken or the threadsbeen injured. r

of applying. the principle of my be employed instead of the one on thelead screw have Other modes invention may veoipl 'ziu'"nod, change beingmade as regards the n'e'cha'n'ism herein disclosed, provided the meansstated by the renewing claim or the equivalent '0? such stated meenebeemployed.

I therefore particularly point out and distinctly Claim as my invention:

v In an automatic,t'appinghiachine, having a ie'a screw assembiyeemprisng n internally threaded sleeve, detach'ably 'affixed on the heirslug ofsuch machine; an e'xt'ernally threaded cylindri'cal'guide element'ope'rativel'y' meuntea with in said sleeve, said element being providedwith a spline'd internal bore; the improvement compr'isin'g meansdetachably depending a splin'e'd spindle from said guide element, withsplines of more and element in operative engagement, said meansincludingajstod bolt inserted in said Samm e "through said' element anda device on said element locking said bolt against rotation.

' MARK GRAVES.

